Mack applied
for certification in early March. With the approval, Mack becomes
the first diesel enginemaker to have all of its heavy-duty models
certified by the EPA.

In April,
Cummins received the first EPA certification for its ISX model.
Caterpillar has since challenged that certification.

To meet EPA
post-October standards, engines must emit no more than 2.5 grams
worth of oxides of nitrogen. Both the Mack on-highway and Cummins
ISX models will employ a form of cooled exhaust gas recirculation
to meet the tougher standards.